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Bmw 520 vs Bmw M550i xdrive auto: reliability comparison

MOT pass rates, common faults and mileage compared from real UK MOT data.

Bmw 520
78%
MOT pass rate · 156,398 vehicles
Bmw M550i xdrive auto
87%
MOT pass rate · 315 vehicles
More reliable
Verdict: On MOT pass rate, the Bmw M550i xdrive auto is the more reliable of the two — 87% pass first time versus 78%. It's one signal among several; check the full breakdown below.

Head to head

Measure Bmw 520 Bmw M550i xdrive auto
MOT pass rate 78% 87% ✓
MOT failure rate 22% 13% ✓
Faults & advisories per test 1.6 0.5 ✓
Dangerous-fault share 3% ✓ 23%
Average mileage 134,460 mi 30,066 mi
Sample size (vehicles) 156,398 315

Most common faults

Bmw 520

  1. Nearside Rear Tyre worn close to the legal limit (4.1.E.1)
  2. Offside Rear Tyre worn close to the legal limit (4.1.E.1)
  3. Offside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  4. Nearside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  5. Under-trays fitted obscuring some underside components
  6. Nearside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))

Bmw M550i xdrive auto

  1. Rear Prop shaft flexible coupling slightly deteriorated (6.1.7 (d) (i))
  2. Nearside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  3. Nearside Front Tyre has a bulge, caused by separation or partial failure of its structure (5.2.3 (d) (ii))
  4. Nearside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  5. Nearside Front Tyre has a cut but not deep enough to reach the ply or cords (5.2.3 (d) (i))
  6. Nearside Rear Nail in tyre

Reliability FAQ

On MOT pass rate, the Bmw M550i xdrive auto is the more reliable of the two — 87% pass first time versus 78%. It's one signal among several; check the full breakdown below.

Full Bmw 520 report Full Bmw M550i xdrive auto report Most reliable cars

Pass rates are computed over completed (pass/fail) MOT tests. Reliability also depends on age, mileage and upkeep — see each model's page for the full picture.